The Serious Engine 1 source code was released by Croteam under GNU GPL v2 in 2016, and this analysis dives into the codebase, focusing on concepts rather than implementation. Serious Sam’s foundation as a multiplayer game makes even its single-player mode a multiplayer experience through clever abstraction. The article delves into elements like demo recording and playback, game state serialization, floating point determinism, tick vs. frame rates, and the intricacies of networked multiplayer using UDP. The Engine’s custom protocol ensures reliability and packet ordering. The Server-Client model in Serious Engine’s multiplayer ensures smooth gameplay even over early internet connections while avoiding issues associated with a pure peer-to-peer model.
https://staniks.github.io/articles/serious-engine-networking-analysis